Pressure and leak testing methods

ABSTRACT

An analysis system includes a fluidic system includes a number of components that are interconnected to form a fluidic system having a plurality of flow paths. An example method of pressure testing the fluidic system includes (a) selecting a flow path from the plurality of flow paths through a flow cell in accordance with a prescribed test protocol; (b) actuating a pump to pressurize a fluid in the selected flow path; (c) generating pressure data representative of the pressure in the selected flow path; and (d) processing the pressure data to determine whether the selected flow path maintains pressure in a desired manner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority under to British (GB) PatentApplication No. 1704763.0, filed Mar. 24, 2017, which claims benefit ofpriority to U.S. Patent Application No. 62/442,542, filed Jan. 5, 2017,as well as benefit of priority under 35 U.S.C. § 119(e) to U.S. PatentApplication No. 62/442,542, filed Jan. 5, 2017, both of which are herebyincorporated by reference herein in their entireties.

BACKGROUND

Instruments have been developed and continue to evolve for sequencingmolecules of interest, particularly DNA, RNA and other biologicalsamples. In advance of sequencing operations, samples of the moleculesof interest are prepared in order to form a library or template whichwill be mixed with reagents and ultimately introduced into a flow cellwhere individual molecules will attach at sites and be amplified toenhance detectability. The sequencing operation, then, includesrepeating a cycle of steps to bind the molecules at the sites, tag thebound components, image the components at the sites, and process theresulting image data.

In such sequencing systems, fluidic systems (or subsystems) provide theflow of substances (e.g., the reagents) under the control of a controlsystem, such as a programmed computer and appropriate interfaces.

SUMMARY

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims.

In some implementations, a system may be provided that includes aninterface to fluidically connect with a flow cell that to supportanalytes of interest in an analysis system, the fluidic interfaceincluding a plurality of flow paths and a plurality of effluent lines,each flow path to fluidically connect with one or more channels of theflow cell when the flow cell is mounted in the analysis system and eacheffluent line to fluidically connect with one of the channels of theflow cell when the flow cell is mounted in the analysis system; aselector valve fluidically connected with plurality of flow paths, theselector valve to controllably select one of the flow paths; one or morepumps, each pump fluidically connected with one or more of the effluentlines; a pressure sensor in fluidic communication with the selected flowpath, the pressure sensor to detect pressure in the selected flow pathand to generate pressure data based on the detected pressure; andcontrol circuitry, the control circuitry having one or more processorsand a memory to store, or storing, computer-executable instructionswhich, when executed by the one or more processors, control the one ormore processors to: control the one or more pumps so as to pressurizethe selected flow path according to a prescribed test protocol; andaccess the pressure data and to determine whether the selected flow pathmaintains pressure in a desired manner.

In some implementations of the system, the one or more pumps may includeat least one syringe pump. In some implementations of the system, thefluid may include air.

In some implementations of the system, the memory may be to store, ormay store, further computer-executable instructions which, when executedby the one or more processors, further control the one or moreprocessors to cause the one or more pumps to pressurize the selectedflow path in a stepwise manner, with each pressure step having a higherpressure than the previous pressure step.

In some implementations of the system, the memory may be to store, ormay store, further computer-executable instructions which, when executedby the one or more processors, further control the one or moreprocessors to cause the selector valve to successively select differentflow paths of the plurality of flow paths to be pressure-tested inaccordance with the prescribed test protocol.

In some implementations of the system, the plurality of flow paths mayinclude a first flow path through one channel of the flow cell when theflow cell is mounted to the interface, and a second flow path through asecond channel of the flow cell when the flow cell is mounted to theinterface, in which the second flow path may be different from the firstflow path.

In some implementations of the system, the plurality of flow paths mayinclude a third flow path that includes both the first and the secondflow paths.

In some implementations of the system, the selector valve may be furtherfluidically connected with a bypass line that bypasses the flow cell,and the memory may be to store, or may store, furthercomputer-executable instructions which, when executed by the one or moreprocessors, further control the one or more processors to cause theselector valve to select the bypass line to be pressure-tested inaccordance with the prescribed test protocol.

In some implementations of the system, the system may include a secondvalve that is fluidically connected with an inlet to the selector valve,in which the second valve is to seal the selected flow path at thesecond valve for pressure-testing of the selected flow path between thesecond valve and the pump.

In some implementations, a system may be provided that includes a flowcell to support analytes of interest; a selector valve fluidicallyconnected with the flow cell, the selector valve to controllably selecta flow path through the flow cell from a plurality of flow paths throughthe flow cell that are selectable by the selector valve; one or morepumps fluidically connected with the flow cell, the one or more pumps topressurize a fluid in the selected flow path in accordance with aprescribed test protocol; a pressure sensor fluidically connected withthe selected flow path, the pressure sensor to detect pressure in theselected flow path and to generate pressure data based on the detectedpressure; and control circuitry, the control circuitry having one ormore processors and a memory to store, or storing, computer-executableinstructions which, when executed by the one or more processors, controlthe one or more processors to: cause the selector valve to successivelyselect different flow paths of the plurality of flow paths through theflow cell in accordance with the prescribed test protocol, cause the oneor more pumps to be actuated so as to successively pressurize theselected flow paths in accordance with the prescribed test protocol,access the pressure data, and determine whether each of the selectedflow paths maintains pressure in a desired manner based on the pressuredata.

In some implementations of the system, the fluid may include air.

In some implementations of the system, the memory may be to store, ormay store, further computer-executable instructions which, when executedby the one or more processors, further control the one or moreprocessors to cause the one or more pumps to pressurize each of theselected flow paths in a stepwise manner using a plurality of pressuresteps, with each pressure step for each selected flow path having ahigher pressure than the previous pressure step for that selected flowpath.

In some implementations of the system, the plurality of flow paths mayinclude a first flow path through one channel of the flow cell and asecond flow path through a second channel of the flow cell, in which thesecond flow path may be different from the first flow path.

In some implementations of the system, the plurality of flow paths mayinclude a third flow path that includes both the first and the secondflow paths.

In some implementations of the system, the selector valve may be furtherfluidically connected with a bypass line that bypasses the flow cell,and the selector valve may be controllable to select the bypass line tobe pressure tested in accordance with the prescribed test protocol.

In some implementations, a method may be provided that includesimplementing a stored prescribed test protocol that includes: (a)selecting a flow path from a plurality of flow paths through a flow cellin accordance with the prescribed test protocol; (b) actuating a pump topressurize a fluid in the selected flow path; (c) generating pressuredata representative of the pressure in the selected flow path; and (d)processing the pressure data representative of the pressure in theselected flow path to determine whether the selected flow path maintainspressure in a desired manner.

In some implementations of the method, actuating the pump may includeactuating the pump to pressurize the selected flow path in a stepwisemanner using a plurality of pressure steps.

In some implementations of the method, the method may further includerepeating (a)-(d) for different flow paths through the flow cell toseparately determine whether each selected flow path maintains pressurein a desired manner.

In some implementations of the method, the plurality of flow paths mayinclude a first flow path through one channel of the flow cell and asecond flow path through a second channel of the flow cell, in which thesecond flow path may be different from the first flow path.

In some implementations of the method, the method may further includeselecting a bypass line to be pressure tested in accordance with theprescribed test protocol, actuating the pump to pressurize a fluid inthe bypass line, generating pressure data representative of the pressurein the bypass line, and processing the pressure data representative ofthe pressure in the bypass line to determine whether the bypass linemaintains pressure in a desired manner, in which the bypass line may notflow through the flow cell.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical overview of an example sequencing system inwhich the disclosed techniques may be employed;

FIG. 2 is a diagrammatical overview of an example fluidic system of thesequencing system of FIG. 1;

FIG. 3 is a diagrammatical overview of an example of processing andcontrol system of the sequencing system of FIG. 1;

FIG. 4 is a diagrammatical overview of another implementation of aportion of a fluidic system for the example sequencing system of FIG. 1;

FIGS. 5A-C are diagrams illustrating flow paths through the valving foran example syringe pump of the example fluidic system of FIG. 4 invarious positions;

FIGS. 6A-F are cross-sectional diagrams of an implementation of anexample common line selection valve of the fluidic system illustrated inFIG. 4 in various positions;

FIG. 7 is a flow diagram illustrating an implementation of an exampleprocess for pressure testing the fluidic system of FIG. 4;

FIG. 8 is a flow diagram illustrating an implementation of an exampleprocess to prepare the fluidic system of FIG. 4 for pressure testing;

FIG. 9 is a flow diagram illustrating an implementation of an exampleprocess for performing pressure testing to determine a leak rate of theparticular flow path of the fluidic system of FIG. 4;

FIG. 10 is a graph illustrating an example of pressure in a flow path ofthe fluidic system of FIG. 4 as a function of time during pressuretesting, as set forth in FIG. 9;

FIGS. 11-14 are diagrammatical overviews of implementations of flowpaths of the of the example fluidic system of FIG. 4 undergoing pressuretesting different flow paths in different configurations; and

FIG. 15 is a flow diagram illustrating an implementation of an examplesystem control method that involves the use of aproportional-integral-derivative controller (PID) to controlpressurization of the flow path during pressure testing.

DETAILED DESCRIPTION

FIG. 1 illustrates an implementation of a sequencing system 10configured to process molecular samples that may be sequenced todetermine their components, the component ordering, and generally thestructure of the sample. The system includes an instrument 12 thatreceives and processes a biological sample. A sample source 14 providesthe sample 16 which in many cases will include a tissue sample. Thesample source may include, for example, an individual or subject, suchas a human, animal, microorganism, plant, or other donor (includingenvironmental samples), or any other subject that includes organicmolecules of interest, the sequence of which is to be determined. Thesystem may be used with samples other than those taken from organisms,including synthesized molecules. In many cases, the molecules willinclude DNA, RNA, or other molecules having base pairs the sequence ofwhich may define genes and variants having particular functions ofultimate interest.

The sample 16 is introduced into a sample/library preparation system 18.This system may isolate, break, and otherwise prepare the sample foranalysis. The resulting library includes the molecules of interest inlengths that facilitate the sequencing operation. The resulting libraryis then provided to the instrument 12 where the sequencing operation isperformed. In practice, the library, which may sometimes be referred toas a template, is combined with reagents in an automated orsemi-automated process, and then introduced to the flow cell prior tosequencing.

In the implementation illustrated in FIG. 1, the instrument includes aflow cell or array 20 that receives the sample library. The flow cellincludes one or more fluidic channels, also referred to herein as lanes,that allow for sequencing chemistry to occur, including attachment ofthe molecules of the library, and amplification at locations or sitesthat can be detected during the sequencing operation. For example, theflow cell/array 20 may include sequencing templates immobilized on oneor more surfaces at the locations or sites. A “flow cell” may include apatterned array, such as a microarray, a nanoarray, and so forth. Inpractice, the locations or sites may be disposed in a regular, repeatingpattern, a complex non-repeating pattern, or in a random arrangement onone or more surfaces of a support. To enable the sequencing chemistry tooccur, the flow cell also allows for introduction of substances, such asincluding various reagents, buffers, and other reaction media, that areused for reactions, flushing, and so forth. The substances flow throughthe flow cell and may contact the molecules of interest at theindividual sites.

In the instrument the flow cell 20 is mounted on a movable stage 22that, in this implementation, may be moved in one or more directions asindicated by reference numeral 24. The flow cell 20 may, for example, beprovided in the form of a removable and replaceable cartridge that mayinterface with ports on the movable stage 22 or other components of thesystem in order to allow reagents and other fluids to be delivered to orfrom the flow cell 20. The stage is associated with an optical detectionsystem 26 that can direct radiation or light 28 to the flow cell duringsequencing. The optical detection system may employ various methods,such as fluorescence microscopy methods, for detection of the analytesdisposed at the sites of the flow cell. By way of a non-limitingexample, the optical detection system 26 may employ confocal linescanning to produce progressive pixilated image data that can beanalyzed to locate individual sites in the flow cell and to determinethe type of nucleotide that was most recently attached or bound to eachsite. Other suitable imaging techniques may also be employed, such astechniques in which one or more points of radiation are scanned alongthe sample or techniques employing “step and shoot” imaging approaches.The optical detection system 26 and the stage 22 may cooperate tomaintain the flow cell and detection system in a static relationshipwhile obtaining an area image, or, as noted, the flow cell may bescanned in any suitable mode (e.g., point scanning, line scanning,“step-and-shoot” scanning).

While many different technologies may be used for imaging, or moregenerally for detecting the molecules at the sites, presentlycontemplated implementations may make use of confocal optical imaging atwavelengths that cause excitation of fluorescent tags. The tags, excitedby virtue of their absorption spectrum, return fluorescent signals byvirtue of their emission spectrum. The optical detection system 26 isconfigured to capture such signals, to process pixelated image data at aresolution that allows for analysis of the signal-emitting sites, and toprocess and store the resulting image data (or data derived from it).

In a sequencing operation, cyclic operations or processes areimplemented in an automated or semi-automated fashion in which reactionsare promoted, such as with single nucleotides or with oligonucleotides,followed by flushing, imaging and de-blocking in preparation for asubsequent cycle. The sample library, prepared for sequencing andimmobilized on the flow cell, may undergo a number of such cycles beforeall useful information is extracted from the library. The opticaldetection system may generate image data from scans of the flow cell(and its sites) during each cycle of the sequencing operation by use ofelectronic detection circuits (e.g., cameras or imaging electroniccircuits or chips). The resulting image data may then be analyzed tolocate individual sites in the image data, and to analyze andcharacterize the molecules present at the sites, such as by reference toa specific color or wavelength of light (a characteristic emissionspectrum of a particular fluorescent tag) that is detected at a specificlocation, as indicated by a group or cluster of pixels in the image dataat the location. In a DNA or RNA sequencing application, for example,the four common nucleotides may be represented by distinguishablefluorescence emission spectra (wavelengths or wavelength ranges oflight). Each emission spectrum, then, may be assigned a valuecorresponding to that nucleotide. Based upon this analysis, and trackingthe cyclical values determined for each site, individual nucleotides andtheir orders may be determined for each site. These sequences may thenbe further processed to assemble longer segments including genes,chromosomes, and so forth. As used in this disclosure the terms“automated” and “semi-automated” mean that the operations are performedby system programming or configuration with little or no humaninteraction once the operations are initiated, or once processesincluding the operations are initiated.

In the illustrated implementation, reagents 30 are drawn or aspiratedinto the flow cell through valving 32. The valving may access thereagents from recipients or vessels in which they are stored, such asthrough pipettes or sippers (not shown in FIG. 1). The valving 32 mayallow for selection of the reagents based upon a prescribed sequence ofoperations performed. The valving may further receive commands fordirecting the reagents through flow paths 34 into the flow cell 20. Exitor effluent flow paths 36 direct the used reagents from the flow cell.In the illustrated implementation, a pump 38 serves to move the reagentsthrough the system. The pump may also serve other useful functions, suchas measuring reagents or other fluids through the system, aspirating airor other fluids, and so forth, as discussed in greater detail below.Additional valving 40 downstream of pump 38 allows for appropriatelydirecting the used reagent to disposal vessels or recipients 42.

The instrument further includes a range of circuitry that aids incommanding the operation of the various system components, monitoringtheir operation by feedback from sensors, collecting image data, and atleast partially processing the image data. In the implementationillustrated in FIG. 1, a control/supervisory system 44 includes acontrol system 46 and a data acquisition and analysis system 48. Bothsystems will include one or more processors (e.g., digital processingcircuits, such as microprocessors, multi-core processors, FPGA's, or anyother suitable processing circuitry) and associated memory circuitry 50(e.g., solid state memory devices, dynamic memory devices, on and/oroff-board memory devices, and so forth) that may storemachine-executable instructions for controlling, for example, one ormore computers, processors, or other similar logical devices to providecertain functionality. Application-specific or general purpose computersmay at least partially make up the control system and the dataacquisition and analysis system. The control system may include, forexample, circuitry configured (e.g., programmed) to process commands forfluidics, optics, stage control, and any other useful functions of theinstrument. The data acquisition and analysis system 48 interfaces withthe optical detection system to command movement of the opticaldetection system or the stage, or both, the emission of light for cyclicdetection, receiving and processing of returned signals, and so forth.The instrument may also include various interfaces as indicated atreference 52, such as an operator interface that permits control andmonitoring of the instrument, loading of samples, launching of automatedor semi-automated sequencing operations, generation of reports, and soforth. Finally, in the implementation of FIG. 1, external networks orsystems 54 maybe coupled to and cooperate with the instrument, forexample, for analysis, control, monitoring, servicing, and otheroperations.

It may be noted that while a single flow cell and fluidics path, and asingle optical detection system are illustrated in FIG. 1, in someinstruments more than one flow cell and fluidics path may beaccommodated. For example, in a presently contemplated implementation,two such arrangements are provided to enhance sequencing and throughput.In practice, any number of flow cells and paths may be provided. Thesemay make use of the same or different reagent receptacles, disposalreceptacles, control systems, image analysis systems, and so forth.Where provided, the multiple fluidics systems may be individuallycontrolled or controlled in a coordinated fashion. It is to beunderstood that the phrase “fluidically connected” may be used herein todescribe connections between two or more components that place suchcomponents in fluidic communication with one another, much in the samemanner that “electrically connected” may be used to describe anelectrical connection between two or more components. The phrase“fluidically interposed” may be used, for example, to describe aparticular ordering of components. For example, if component B isfluidically interposed between components A and C, then fluid flowingfrom component A to component C would flow through component B beforereaching component C.

FIG. 2 illustrates an example fluidic system of the sequencing system ofFIG. 1. In the implementation illustrated, the flow cell/array 20includes a series of pathways or lanes 56A and 56B which may be groupedin pairs for receiving fluid substances (e.g., reagents, buffers,reaction media) during sequencing operations. The lanes 56A are coupledto a common line 58 (a first common line), while the lanes 56B arecoupled to a second common line 60. A bypass line 62 is also provided toallow fluids to bypass the flow cell without entering it. As notedabove, a series of vessels or recipients 64 allow for the storage ofreagents and other fluids that may be utilized during the sequencingoperation. A reagent selection valve 66 is mechanically coupled to amotor or actuator (not shown) to allow selection of one or more of thereagents to be introduced into the flow cell. Selected reagents are thenadvanced to a common line selection valve 68 (also referred to as aselector valve) which similarly includes a motor (not shown). The commonline selection valve may be commanded (e.g., signaled, instructed) toselect one or more of the common lines 58 and 60, or both common lines,to cause the reagents 64 to flow to the lanes 56A and/or 56B in acontrolled fashion, or the bypass line 62 to flow one or more of thereagents between the common line selection valve 68 and the pump 38.

Used reagents exit the flow cell through lines (e.g., exit or effluentflow paths 36) coupled between the flow cell/array 20 and the pump 38.In the illustrated implementation, the pump includes a syringe pumphaving a pair of syringes 70 that are controlled and moved by anactuator 72 to aspirate the reagents and other fluids and to expel thereagents and fluids during different operations of the testing,verification and sequencing cycles. The pump assembly may includevarious other parts and components, including valving, instrumentation,actuators, and so forth (not shown). In the illustrated implementation,pressure sensors 74A and 74B sense pressure on inlet lines of the pump,while a pressure sensor 74C is provided to sense pressures output by thesyringe pump.

Fluids used by the system enter a used reagent selection valve 76 fromthe pump. This valve allows for selection of one of multiple flow pathsfor used reagents and other fluids. In the illustrated implementation, afirst flow path leads to a first used reagent receptacle 78, while asecond flow path leads through a flow meter 80 a second used reagentreceptacle 82. Depending upon the reagents used, it may be advantageousto collect the reagents, or certain of the reagents in separate vesselsfor disposal, and the used reagent selection valve 76 allows for suchcontrol.

It should be noted that valving within the pump assembly may allow forvarious fluids, including reagents, solvents, cleaners, air, and soforth to be aspirated by the pump and injected or circulated through oneor more of the common lines, the bypass line, and the flow cell.Moreover, as noted above, in a presently contemplated implementation,two parallel implementations of the fluidics system shown in FIG. 2 areprovided under common control. Each of the fluidics systems may be partof a single sequencing instrument, and may carry out functions includingsequencing operations on different flow cells and sample libraries inparallel.

The fluidics system operates under the command of control system 46which implements prescribed protocols for testing, verification,sequencing, and so forth. The prescribed protocols will be establishedin advance and include a series of events or operations for activitiessuch as aspirating reagents, aspirating air, aspirating other fluids,expelling such reagents, air and fluids, and so forth. The protocolswill allow for coordination of such fluidic operations with otheroperations of the instrument, such as reactions occurring in the flowcell, imaging of the flow cell and its sites, and so forth. In theillustrated implementation, the control system 46 employs one or morevalve interfaces 84 which are configured to provide command signals forthe valves, as well as a pump interface 86 configured to commandoperation of the pump actuator. Various input/output circuits 88 mayalso be provided for receiving feedback and processing such feedback,such as from the pressure sensors 74A-C and flow meter 80.

FIG. 3 illustrates certain of the functional components of thecontrol/supervisory system 44. As illustrated, the memory circuitry 50stores prescribed routines that are executed during testing,commissioning, troubleshooting, servicing, and sequencing operations.Many such protocols and routines may be implemented and stored in thememory circuitry, and these may be updated or altered from time to time.As illustrated in FIG. 3, these may include a fluidics control protocol90 for controlling the various valves, pumps, and any other fluidicsactuators, as well as for receiving and processing feedback fromfluidics sensors, such as valves, and flow and pressure sensors. A stagecontrol protocol 92 allows for moving the flow cell as desired, such asduring imaging. An optics control protocol 94 allows for commands to beissued to the imaging components to illuminate portions of the flow celland to receive returned signals for processing. An image acquisition andprocessing protocol 96 allows for the image data to be at leastpartially processed for extraction of useful data for sequencing. Otherprotocols and routines may be provided in the same or different memorycircuitry as indicated by reference 98. In practice, the memorycircuitry may be provided as one or more memory devices, such as bothvolatile and non-volatile memories. This memory may be within theinstrument, and some may be off-board.

One or more processors 100 access the stored protocols and implementthem on the instrument. As noted above, the processing circuitry may bepart of application-specific computers, general-purpose computers, orany suitable hardware, firmware and software platform. The processorsand the operation of the instrument may be commanded by human operatorsvia an operator interface 101. The operator interface may allow fortesting, commissioning, troubleshooting, and servicing, as well as forreporting any issues that may arise in the instrument. The operatorinterface may also allow for launching and monitoring sequencingoperations.

The fluidics control protocol 90 stored in the memory 50 may alsoinclude diagnostic routines that can be executed by the processor 100 toevaluate the integrity and reliability of the fluidic system. With thisin mind, present implementations are directed toward methods ofoperating the fluidics system of the instrument 12 to isolate and testvarious flow paths (e.g., flow cell channels, common lines, and pumplines) of the fluidic system for potential leaks using pressurized airto determine whether each of the flow paths maintains pressure in adesired manner. Using these diagnostic routines, an operator mayevaluate the fluidic system routinely (e.g., before each use of theinstrument, at the beginning of each day or shift, on weekly or monthlyintervals) or at will, based on a particular concern. Accordingly,present implementations enable the early detection and diagnosis ofpotential fluid leaks. As such, the presently disclosed diagnosticroutines can help to avoid sample loss, data loss, and damage tosensitive components of the instrument 12, which can result from a fluidleak during operation of the instrument 12.

FIG. 4 illustrates a portion of the fluidic system 120 for animplementation of the instrument 12, wherein the arrows are indicativeof the flow of substances (e.g., reagents, buffers, analytes) throughthe various illustrated flow paths during sample analysis. For theimplementation illustrated in FIG. 4, a flow cell array 20 includes twolane pairs, denoted as lane pair A and lane pair B. Each of the two lanepairs includes two respective fluidic channels or lanes, denoted aslanes L1, L2, L3, and L4 in FIG. 4. For the illustrated implementation,the flow cell array 20 is designed to be operated as illustrated in FIG.4, with both lane pairs A and B present in the flow cell 20, or with asingle lane pair (e.g., lane pairs A or B) present in the flow cell 20,as discussed in greater detail below with respect to FIGS. 12-14.Further, the fluidic system 120 illustrated in FIG. 4 includes a numberof inline pressure sensors 122 (e.g., pressure sensors 122A-122E,pressure sensors 74A-C of FIG. 2) that are respectively coupled theeffluent lines 36A, 36B, 36C, and 36D and the bypass line 62. Theseinline pressure sensors 122 are communicatively coupled (e.g., via awired or wireless communication channel) to the processor 100 of thecontrol system 46 and configured to output electronic signals to theprocessor 100 corresponding to the pressure of fluids in the variousflow paths of the fluidic system 120.

Additionally, the pump 38 of the fluidic system illustrated in FIG. 4includes multiple syringe pumps 124 (e.g., syringe pumps 124A and 124B).As illustrated, the syringe pumps 124 each include one or morerespective syringes 126 (e.g., syringes 126A and 126B) that arerespectively actuated by actuators 128 (e.g., actuators 128A and 128B).The illustrated syringe pumps 124 also include valving 130 (e.g.,valving 130A and 130B), which enable the syringe pumps to push or pullfluids into and out of different orifices or ports of the pumps 124. Forexample, FIGS. 5A, 5B, and 5C are diagrams illustrating flow pathsthrough the valving 130 (e.g., valving 130A and 130B) of FIG. 4 indifferent positions. As illustrated, the valving 130 includes two valveunits 132A and 132B (e.g., solenoid valves or other controllable valves)that, as the syringe 126 is actuated, cooperate to aspirate a volume offluids or dispense a volume of fluid into a flow cell port 134 leadingto the flow cell array 20, a used reagent port 136 leading to the usedreagent collection system, or a bypass port 138 leading to the bypassline 62. In FIG. 5A, referred to hereafter as the “I” position, thevalve units 132A and 132B enable the syringe 126 to draw fluid from, orintroduce fluid into, the flow cell port 134. In FIG. 5B, referred tohereafter as the “O” position, the valve units 132A and 132B enable thesyringe 126 to draw fluid from or introduce fluid into, the used reagentport 136. In FIG. 5C, referred to hereafter as the “B” position, thevalve units 132A and 132B enable the syringe 126 draw fluid from orintroduce fluid into the bypass port 138. As generally discussed above,the control system 46 sends control signals to control the actuation ofthe actuators 126 and the valving 130. In certain implementations, thesyringe pumps 124, including the associated valving, may be rated forpressures up to about 22 pounds per square inch gauge (prig); however,in other implementations, other pressures may be used in accordance withthe present disclosure.

The common line selection valve 68 of the implementation illustrated inFIG. 4 enables fluid coupling of a reagent flow path 140 (disposedbetween the reagent selector valve (RSV) 66 and the common lineselection valve 66), the first common line 58, the second common line60, the bypass line 62, and an air inlet 142, in various manners. Forexample, FIGS. 6A-F illustrate a cross-sectional diagrammatical view ofthe implementation of the common line selection valve 68 illustrated inFIG. 4 in various positions or orientations. Different shading orhashing is used to distinguish between the ports 150 of the common lineselection valve 68, which include: a bypass port 150A that isfluidically coupled to the bypass line 62, an air port 150B that isfluidically coupled to the air inlet 142, a lane pair A port 150C thatis fluidically coupled to the first common line 58 leading to lane pairA, an RSV port 150D that is fluidically coupled to the reagent selectorvalve 66 via the reagent flow path 140, and a lane pair B port 150E thatis fluidically coupled to the second common line 60 leading to lane pairB.

The common line selection valve 68 illustrated in FIGS. 6A-F has arounded, central portion 152 that rotates about a central point 154 andthat includes various channels 156. The central portion 152 is firmlysealed against ports 150 such that fluid does not leave a port 150unless a channel 156 is suitably aligned to enable flow to another port150. For example, the orientation of the common line selection valve 68illustrated in FIG. 6A, referred to hereafter as the “RSV to Lane PairA” position, fluidically couples the RSV port 150D to the bypass port150A. The orientation illustrated in FIG. 6B, referred to hereafter asthe “RSV to Lane Pair B” position, fluidically couples the RSV port 150Dto the lane pair B port 150E. The orientation illustrated in FIG. 6C,referred to hereafter as the “RSV to Lane Pairs A & B” position,fluidically couples the RSV port 150D to the to both the lane pair Aport 150C and the lane pair B port 150E. As such, the orientationsillustrated in FIGS. 6A-C enable the implementation of the fluidicsystem 120 illustrated in FIG. 4 to operate, as described above, todirect fluids received from the reagent selection valve 66 through asingle lane pair (e.g., lane pairs A or B) or both lane pairs A and Bsimultaneously.

The orientations of the common line selection valve 68 illustrated inFIGS. 6A-F, as well as other potential positions, may also be useful fordiagnostic purposes to enable the processor 100 to isolate, prepare, andpressure test the various flow paths of the fluidic system. Inparticular, the orientation illustrated in FIG. 6D, referred tohereafter as the “Air to Lane Pairs A & B” position, fluidically couplesthe air port 150B to both lane pair A port 150C and lane pair B port150E, which is useful to dry the flow cell 20 prior to pressure testing,as discussed below. The orientation illustrated in FIG. 6E, referred tohereafter as the “Air to Bypass” position, fluidically couples air port150B to the bypass port 150A, which is useful to enable air to beintroduced into the fluidic system during certain pressure tests, asdiscussed below. The orientation illustrated in FIG. 6F, referred tohereafter as the “RSV to Bypass” position, fluidically couples the RSVport 150D to the bypass port 150A, which is useful during pressuretesting of the bypass line 62, as discussed below.

As mentioned, the fluidics control protocol 90 stored in the memory 50may include diagnostic routines that can be executed by the processor100 to evaluate the fluidic system 120 for potential leaks. FIG. 7 is aflow diagram representing an implementation of a process 160 forpressure testing the fluidic system 120 of the instrument 12 illustratedin FIG. 4. The illustrated process 160 begins with preparing system forpressure testing of a particular flow path (block 162). While discussedin detail below with respect to FIG. 8, in block 162, processor 100 mayisolate and prepare the particular flow path of the fluidic system 120,as well as otherwise ensure that the instrument 12 is ready to beginpressure testing. Once preparation is successfully completed, theprocessor 100 may perform pressure testing to determine a leak rate ofthe particular flow path (block 164). While discussed in detail belowwith respect to FIG. 9, in block 164, processor 100 may pressurize theparticular flow path of the fluidic system 120 to a target pressure,measure a change in pressure over a known period of time, and determinea leak rate based on the measured change in pressure.

Continuing through the process 160 illustrated in FIG. 7, the processor100 may then determine whether the leak rate is less than or equal to apredetermined threshold value (block 166). If the determined leak rateis greater than the predetermined threshold value, the processor 100 mayterminate further pressure testing and record details regarding thefailure (block 168). In certain implementations, the predeterminedthreshold value for the leak rate may be calculated based, at least inpart, on the volume of the particular flow path being tested and theviscosity of the fluids that traverse the fluidic system duringoperation (e.g., reagents, buffers, analytes) relative to the viscosityof air. For example, if a leak rate of the fluids that traverse thefluidic system during operation should be maintained at or belowapproximately 8 microliters per minute (μL/min) for a four-laneconfiguration of the fluidic system 120, as illustrated in FIG. 4, basedon the difference between the viscosity of the fluids that traverse thefluidic system during operation (e.g., reagents, buffers, analytes) andair, the predetermined threshold value may be approximately 0.02 poundsper square inch per second (psi/sec). By further example, if a leak rateof the fluids that traverse the fluidic system during operation shouldbe maintained at or below approximately 4 microliters per minute(μL/min) for a two-lane configuration with only one lane pair A or Bloaded (approximately half the volume of the four-lane configuration),based on the viscosity difference, the predetermined threshold value mayagain be approximately 0.02 psi/sec.

If the determined leak rate is less than or equal to the predeterminedthreshold value, the processor 100 may determine whether additionalpressure tests of other flow paths should be performed (block 170). Ifno further pressure testing is to be performed, then the processor 100may terminate pressure testing and record details regarding thesuccessful pressure testing (block 172). If additional pressure testingis to be performed, the processor 100 may select the next flow path tobe tested (block 174), and then the actions set forth in blocks 162,164, 166, and 170 may be repeated, as indicated by the arrow 176. Incertain implementations, the processor 100 may prompt the operator toperform one or more physical operations (e.g., load a lane pair, removea lane pair, remove/load multiple lane pairs, e.g., where multiple lanepairs are in a single flow cell cartridge) to enable a particular flowpath to be tested.

FIG. 8 is a flow diagram illustrating an implementation of a process 180for preparing the fluidic system 120 for pressure testing, correspondingto block 162 of FIG. 7. The illustrated process 180 begins with sendingcontrol signals and/or receiving sensor data to verify the state of thesystem (block 182). This may include, for example, ensuring that theappropriate number of lane pairs are present in the flow cell 20. Incertain implementations, as illustrated, the process 184 may include theprocessor 100 sending control signals to the fluidic system 120 to drythe system before pressure testing (block 184). For example, asmentioned above with respect to FIG. 6D, the processor 100 may provideappropriate control signals to orient the common line selection value 68in the “Air to Lane Pairs A & B” position and the reagent selectionvalve 66 in a blocked or closed position, while actuating the pump 38 todraw and remove liquid from the flow paths of the fluidic system,thereby drawing air into the system through the air inlet 142.

The process 180 illustrated in FIG. 8 continues with the processor 100receiving baseline data from sensors on an isolated flow path for sensorcalibration (block 186). For example, unless already in the correctposition, the processor 100 may first provide suitable control signalsto the common line selection valve 68 to fluidically couple the flowpath to be pressure tested, or the entire fluidic system 120, to the airinlet 142 and equalize the pressure in the flow path with ambientatmospheric pressure. For example, the common line selection valve 68may be disposed in the “Air to Lane Pairs A & B” position, illustratedin FIG. 6D, when the flow path to be tested includes a lane pair, andmay be disposed in the “Air to Bypass” position, illustrated in FIG. 6E,when the flow path to be tested includes the bypass line 62. Afterfluidically coupling the flow path to be pressure tested to the airinlet, one or more pressure sensors 122A-122E of the fluidic system 120,as illustrated in FIG. 4, may be used to measure a baseline pressure(e.g., ambient pressure) for calibration.

Returning to FIG. 8, the illustrated process 180 concludes with theprocessor 100 sending control signals to appropriately orient the commonline selection valve 68 and/or the regent selection valve 66 to isolatethe flow path to be pressure tested (block 180). As discussed above withrespect to FIG. 6A-F, the common line selection valve 68 may be orientedin a number of different positions to selectively fluidically couple,and selectively isolate, the various flow paths of the fluidic system120. The isolation set forth in block 188 is discussed in further detailbelow with respect to FIGS. 11-14.

FIG. 9 is a flow diagram illustrating an implementation of a process 190for performing pressure testing to determine a leak rate of theparticular flow path of the fluidic system 120, corresponding to block164 of FIG. 7. The illustrated process 190 begins with the processor 100sending control signals to actuate one or more portions of the pump 38(e.g., valving 130 and/or syringes 126 of at least one of the syringepumps 124) to pressurize the flow path being pressure tested with air toa predetermined target pressure (block 192). It may be appreciated thatthe target pressure may correspond to a pressure that the fluidic system120 experiences during normal operation, or may correspond to a pressurethat is greater than (e.g., two times, three times, etc.) the pressurethat the fluidic system 120 experiences during normal operation. Forexample, in an implementation, if the fluidic system 120 experiencesapproximately 9 psig of pressure during sample analysis, then, incertain implementations, the target pressure for pressure testing may beapproximately 18 psig to provide a more intensive pressure test of theflow path.

As discussed in greater detail below, for pressure testing differentconfigurations of the fluidic system 10, a particular syringe pump 124(e.g., syringe pump 124A or 124B) may be used to pressurize the flowpath. In other implementations, both syringe pumps may cooperate topressurize the flow path being tested. Additionally, the processor 100may determine the current pressure within the flow path based onpressure measurements received from pressure sensors 122. In cases inwhich the flow path being pressure tested includes multiple pressuresensors 122, the processor 100 may use pressure measurements from aparticular pressure sensor, for example, to compare the measurementsfrom multiple pressure sensors to verify operation of the pressuresensors.

Further, while other implementations may include a different pumpingmechanism, the syringe pumps 124 of the implementation of the fluidicsystem 120 illustrated in FIG. 4 generally increase the pressure in theflow path being tested in discrete pressure steps. For example, FIG. 10is a graph 194 illustrating pressure (psi) for lanes L1-L4 asrespectively measured by the pressure sensors 122A-122D in a flow pathof the fluidic system 10 of the instrument 12 as a function of time(sec) during the pressure testing described by the method 190 of FIG. 9.The pressurization set forth in block 192 of FIG. 9 is denoted by thepre-measurement region 196 of the graph 194 of FIG. 10. Morespecifically, the region 196 includes repeated cycles during which,first, pressure in the flow path is relatively constant as air isaspirated into the syringe 126 from the atmosphere, as indicated in theregion 198. The valving is then actuated to cause the syringe 126 to befluidically connected with the flow path. Then, pressure in the flowpath equilibrates as pressurized air in the flow path mixes withlower-pressure air in the syringe, as indicated in the region 200.Subsequently, pressure in the flow path increases as air from thesyringe is dispensed into the flow path, as indicated in the region 202.This repeated pattern results in the curves 204 of the graph 194demonstrating pressure steps 206. It may be appreciated that, if theprocessor 100 determines that the fluidic system is not able to bepressurized to the target pressure, then the pressure test may beterminated with a failure indication.

Turning briefly back to FIG. 9, in certain implementations, theprocessor 100 may wait a predetermined amount of time to allow pressureto equilibrate (block 210) before proceeding with the process 190. Asshown by the graph 194 of FIG. 10, while the curves 204 representing thepressures of the lanes L1-L4 closely trace one another and are notwell-resolved, the curves differ from one another most during (andbriefly after) the opening of the valving 130 of the syringe pump 124(e.g., during the region 200). In certain implementations, rather thanwait a predetermined amount of time, the processor 100 instead may waituntil the pressure measurements received from each of the lanes L1-L4are the same, within an acceptable tolerance.

Proceeding through the process 190 illustrated in FIG. 9, the processor100 receives measurement data from at least one of the pressure sensors122 positioned along the selected flow path to determine a firstpressure (block 212). The processor 100 then waits a predeterminedamount of time to allow the pressure to decay (block 214) beforereceiving measurement data from at least one of the sensors on selectedflow path to determine a second pressure (block 216). Returning to FIG.10, the measurement region 220 is indicated on the graph 194 andincludes the actions set forth in blocks 212, 214, and 216 of FIG. 9. Asillustrated, the first pressure measurement is collected (indicated bythe arrow 222), and after a predetermined amount of time passes(measurement or decay time, indicated by the region 224), the secondpressure measurement is collected (indicated by the arrow 226). Forexample, the predetermined amount of time should be sufficiently long toenable the detection of a leak rate greater than a predeterminedthreshold (e.g., approximately 0.02 psi/sec at approximately 18 psig),in accordance with the speed and resolution of the pressure sensors 122of the fluidic system 120. In other implementations, any suitable numberof pressure measurements may be collected by the processor 100 from anysuitable number of pressure sensors 122 to determine the leak rate.

As illustrated in FIG. 9, after collecting the second pressuremeasurement, the processor 100 continues through the process 190 bysending control signals to move the common line selection valve 68,actuate valving 130 and/or syringes 126 of at least one of the syringepumps 124 to evacuate the pressurized air from the flow path (block230). This corresponds to the post-measurement region 232 indicated inthe graph 194 of FIG. 10. More specifically, the post-measurement region232 includes repeated cycles with time periods 234 during which pressuredecreases as air from the flow path is aspirated into the syringe,followed by time periods 236 when pressure in the flow path isrelatively constant as air is aspirated from the syringe 126 and intothe atmosphere after the syringe input/output is switched from the flowpath to the air inlet, for example. The process 190 illustrated in FIG.9 concludes with the processor 100 calculating leak rate based on thefirst and second pressure measurements (block 240). For example, theprocessor 100 may calculate the leak rate by dividing the differencebetween the first and second pressure measurements by the measurementtime.

As mentioned above with respect to block 188 of FIG. 8, the processor100 is capable of sending control signals to suitably orient the commonline selection valve 68 and/or the regent selection valve 66 to isolatethe flow path to be pressure tested. FIGS. 11-14 are diagrammaticaloverviews of particular isolated flow paths of the implementation of thefluidic system 120 of FIG. 4 undergoing pressure testing in differentconfigurations. In the figures, the components of the flow path beingpressure tested are bolded or highlighted.

FIG. 11 indicates an example of a flow path 250 of the fluidic system120 that can be pressure tested when both lane pairs A and B are presentin the flow cell 20. The illustrated flow path 250 includes the firstand second common line 58 and 60, the lanes L1, L2, L3 and L4 of lanepairs A and B, the effluent lines 36A-D, and the syringe pumps 124. Asillustrated, reagent selection valve 66 is in a closed or blockedposition, the common line selection valve 68 is in the RSV to Lane PairsA & B position illustrated in FIG. 6C, and the valving 130A of thesyringe pump 124A is in a closed or blocked position. Furthermore, thevalving 130B of the syringe pump 124B is in the B position, and theactuator 128B and the valving 130B are suitably actuated to aspirate airthrough the bypass port 138 and then dispense the air through the lanepair port 134, as discussed above with respect to FIG. 5C. The commonline selector valve 68 may be actuated, in tandem, to switch betweenfluidically connecting the bypass line 62/bypass port 138 with the airinlet 142 (for air aspiration) and fluidically connecting the lane pairsAB with the reagent flow path 140 (for pressure testing). Alternatively,the bypass port of the valving 130B may instead not be fluidicallyconnected with the bypass line, but may simply connect with ambient air,allowing air to be aspirated directly into the syringe pump 124B withoutneeding to use the bypass line 62 or actuate the common line selectorvalve 68. Accordingly, the entire flow path indicated in FIG. 11 can bepressure tested in the manner set forth above.

FIG. 12 indicates an example of a flow path 260 of the fluidic system120 that can be pressure tested when only lane pair A is present orloaded into the flow cell array 20. The illustrated flow path 260includes the first common line 58, the lanes L1 and L2 of lane pair A,effluent lines 36A and 36B, and syringe pump 124A. As illustrated, thecommon line selection valve 68 is in the Air to Bypass positionillustrated in FIG. 6E. Furthermore, the valving 130A of the syringepump 124A is in the B position, and the actuator 128A is suitablyactuated to aspirate air through the bypass port 138 and then dispensethe air through the flow cell port 134 after the valving 130A isactuated to connect with the effluent lines 36A and 36B, as discussedabove with respect to FIGS. 5C and 5A. Accordingly, the entire flow path260 indicated in FIG. 12 can be pressure tested in the manner set forthabove.

FIG. 13 indicates an example of a flow path 270 of the fluidic system120 that can be pressure tested when only lane pair B is present orloaded into the flow cell array 20. The illustrated flow path 270includes the reagent flow path 140, the second common line 60, the lanesL3 and L4 of lane pair B, effluent lines 36C and 36D, and syringe pump124B. As illustrated, the reagent selection valve 66 is in a closed orblocked position, the common line selection valve 68 is in the RSV toLane Pair B position illustrated in FIG. 6B. Furthermore, the valving130B of the syringe pump 124B is in the B position, and the actuator128B is suitably actuated to aspirate air through the bypass port 138and dispense the air through the flow cell port 134 when the valve 130Bis then actuated to the I position (see FIG. 5A). The common lineselector valve 68 may be actuated, in tandem, to switch betweenfluidically connecting the bypass line 62/bypass port 138 with the airinlet 142 (for air aspiration) and fluidically connecting lane pair Bwith the reagent flow path 140 (for pressure testing). Alternatively, insome implementations, the valving 130B may have a bypass port thatsimply opens onto ambient air and is not fluidically connected with thebypass line 62, thereby allowing air to be aspirated directly into thesyringe pump 124B through the bypass port without traveling through thebypass line and without activation of the common line selector valve 68.Accordingly, the entire flow path 270 indicated in FIG. 13 can bepressure tested as set forth above.

FIG. 14 indicates an example of a flow path 280 of the fluidic system120 that can be pressure tested when no lane pairs are loaded into theflow cell array 20. The illustrated flow path 280 includes the bypassline 62, the reagent flow path 140, and syringe pump 124A. Asillustrated, the reagent selection valve 66 is in a closed or blockedposition, the common line selection valve 68 is in the RSV to Bypassposition illustrated in FIG. 6F. Furthermore, the valving 130A of thesyringe pump 124A is in the B position, and the actuator 128A issuitably actuated to aspirate air through the flow cell port 134 anddispense the air through the bypass port 138. The common line selectorvalve 68 may be actuated, in tandem, to switch between fluidicallyconnecting the bypass line 62/bypass port 138 with the air inlet 142(for air aspiration) and fluidically connecting the bypass line 62 withthe reagent flow path 140 (for pressure testing). Accordingly, theentire flow path 280 indicated in FIG. 14 can be pressure tested in themanner described above. It is to be understood that in the aboveexamples, the same tests may be run even if one or both of the flow lanesets that are described as not being present actually are present. Forexample, if both sets of flow lanes are present, each set may beindividually pressure tested. This may, for example, be of use whenthere is a leak detected—individual flow lane tests may be run to tryand narrow down where the leak is. It is also to be understood thatdifferent segments of the flow paths may be tested in othercombinations, e.g., the flow path 140 may be added or omitted from anyof the flow paths in any of the above pressure tests. It is to befurther understood that the flow paths used (and the valving actuated inorder to establish such flow paths) in order to aspirate air into thepumps for pressure testing may vary from what is discussed above—inimplementations where multiple pumping cycles are needed to adequatelypressurize the selected flow paths, any combination of flow paths may beused to convey air to the pumps for pressurization of the tested flowpath, as long as the flow path(s) used for air aspiration is keptfluidically isolated from the flow path being tested.

It may be appreciated that pressurization of the flow path of thefluidic system 120 for pressure testing, as set forth in block 192 ofFIG. 9, could reasonably be implemented using proportional pressurecontrol mechanisms. However, it is presently recognized thatproportional control can fail to be sufficiently robust to deal with thesubstantial differences between the volumes of the various flow paths ofthe fluidic system 120 that may be pressure tested, resulting inpressure test runs that fail to reach the target pressure and/or inwhich the pressure over-corrects and oscillates around the targetpressure. As such, in certain implementations, the pressurization setforth in block 120 may be implemented using aproportional-integral-derivative controller (PID controller). Forexample, in certain implementations, effective pressure control for thedisclosed pressure testing may incorporate the use of a robust systemcontrol method and a PID controller (e.g., integrated into orcommunicatively coupled to the processor 100) to achieve the targettesting pressure in the flow path being tested. It is presentlyrecognized that this configuration improves the ability of the fluidicsystem 120 to efficiently reach the target pressure while avoidingunnecessary pressure oscillations and pressure instabilities despitesignificant differences in the volumes of different flow paths of thefluidic system 120 that may be pressure tested.

By specific example, in an implementation, the pressurization of block192 in FIG. 9 may be implemented to suitably pressurize a flow path to atarget pressure for leak testing, as presently disclosed. FIG. 15 is aflow diagram illustrating an implementation of a system control method300 at least partially executable by a PID (e.g., part of processingcircuitry 100) to perform the actions set forth in block 192 of FIG. 9.The illustrated method 300 begins with the processor 100 receiving(block 302) a first measurement from one or more pressure sensors122A-122E disposed along the flow path being pressure tested.Subsequently, the processor 100 may send (block 304) control signals tosuitably actuate the valving 130 and the actuator 128 of a syringe pump124 to cause the syringe pump 124 to perform a single cycle or stroke topressurize the flow path. The illustrated method 300 continues with theprocessor 100 receiving (block 306) a second measurement from one ormore pressure sensors 122A-122E disposed along the flow path beingpressure tested. Using the first and second measurements, the processor100 may calculate (block 308) a change in pressure per stroke of thesyringe pump 124.

The method 300 continues with the processor 100 calculating the PE(pressure error) (block 310), which is a value that is indicative of howaggressively the gap between the current pressure and the targetpressure should be closed. In certain implementations, PE may becalculated according to equation 1:PE=Gain_(P)*error+Gain_(I)*integral+Gain_(D)*derivativePE=Gain_(P)*error+Gain_(P)*integral+Gain_(D)*derivative,  Eq.1

in which the values of GainP, GainI, and GainD are specific to theconfiguration of the fluidic system 120. For example, in certainimplementations, GainP is approximately 1.0, GainI is approximately0.016, and GainD is approximately 1.0; however, in otherimplementations, different values may be used. In the present context,the term “approximately” is intended to mean that the values indicatedare not exact and the actual value may vary from those indicated (e.g.,±10%, ±5%, ±2%, or ±1%) in a manner that does not materially alter theoperation concerned. In certain implementations, the GainP may be set toa small value to avoid overshooting the target pressure, while the GainIand GainD values are tuned to incrementally close in on the targetpressure.

In certain implementations, the error, integral, and derivative valuesmay be respectively calculated via the PID according to equations 2, 3,and 4:

$\begin{matrix}{{{error} = {{{target\_ pressure} - {measured\_ pressureerror}} = {{target\_ pressure} - {measured\_ pressure}}}},} & {{Eq}.\mspace{14mu} 2} \\{{{integral} = {{{integral}_{previous} + {{error}*\Delta\;{tintegral}}} = {{integral}_{previous} + {{error}*\Delta\; t}}}},} & {{Eq}.\mspace{14mu} 3} \\{{{derivative} = {{\frac{\left( {{error} - {error}_{previous}} \right)}{\Delta\; t}{derivative}} = \frac{\left( {{error} - {error}_{previous}} \right)}{\Delta\; t}}},} & {{Eq}.\mspace{14mu} 4}\end{matrix}$

where integralprevious is the previously calculated integral value,errorprevious is the previously calculated error value, and Δt is thetime interval between error calculations (the “previous” values mayinitially be set to zero when the pressurization routine first begins).As indicated by block 312, a positive PE value may indicate that thepressure should be increased (block 314) to reach the target pressure,while a negative PE value may indicate that the pressure should bedecreased (block 316) to reach the target pressure. However, beforeincreasing or decreasing the pressure in the flow path, the processor100 first determines whether the PE value is within a predeterminedtolerance value (e.g., ±0.5 psig) of the target pressure. For example,as indicated in block 318, if processor 100 determines that the positivePE value not greater than the predetermined tolerance value, then theprocessor 100 may proceed to block 210 of the pressure testing method190 illustrated in FIG. 9. Similarly, as indicated in block 320, ifprocessor 100 determines that the negative PE value is greater than thenegative predetermined tolerance value, then the processor 100 may alsoproceed to block 210.

If the processor 100 determines in block 318 that the positive PE valueis greater than the predetermined tolerance value (e.g., 0.5 psig), thenthe processor 100 may provide suitable control signals to the syringepump 124 to decrease the pressure in the flow path (block 316).Similarly, if the processor 100 determines in block 320 that thenegative PE value is less than the negative predetermined tolerancevalue (e.g., −0.5 psig), then the processor 100 may provide suitablecontrol signals to the syringe pump 124 to increase the pressure in theflow path (block 314). In both situations, the processor 100 may sendcontrol signals to actuate the valving 130 to enable the syringe pump124 to aspirate air from a particular port (e.g., the flow cell port 134or the bypass port 138), and again actuate the valving 130 to enable thesyringe pump 124 to dispense the air into another particular port (e.g.,the flow cell port 134 or the bypass port 138) to suitably increase ordecrease the pressure in the flow path, as discussed above. Depending onthe PE value, the processor 100 may utilize full strokes of the syringepump 124 or may calculate a pump position that is less than a fullstroke to reach the target pressure. For example, in certainimplementations, the processor 100 may calculate the pump positionaccording to equation 5:

$\begin{matrix}{{{PumpPosition} = {{{{ROUND}\left( {{ABS}\left( \frac{{Gain}_{P}*{PE}}{dPdStep} \right)} \right)}{PumpPosition}} = {{ROUND}\left( {{ABS}\left( \frac{{Gain}_{P}*{PE}}{dPdStep} \right)} \right)}}},} & {{Eq}.\mspace{14mu} 5}\end{matrix}$

where ROUND is a rounding function that rounds a real value to thenearest integer value, and ABS is an absolute value function.Additionally, dPdStep may be calculated according to equations 6:

$\begin{matrix}{{{dPdStep} = {{{{ABS}\left( \frac{\Delta\; P}{{PumpPosition}_{\max}} \right)}{dPStep}} = {{ABS}\left( \frac{\Delta\; P}{{PumpPosition}_{\max}} \right)}}},} & {{Eq}.\mspace{14mu} 6}\end{matrix}$

where ΔP is a difference between a current measured pressure (e.g.,second measurement of block 306) and a previously measured pressure(e.g., first measurement of block 302) in the flow path, andPumpPositionmax is the maximum position of the actuator 130 of thesyringe pump 124 (e.g., 6000 steps). Additionally, the processor 100 maykeep a track of the number of cycles (e.g., full or partial strokes ofthe syringe pump 124) for each pressure increase (as set forth in block314) and each pressure decrease (as set forth in block 316).

After actuating the syringe pump 124 to increase or decrease thepressure in the flow path, the method 300 continues with the processor100 receiving another measurement from one or more pressure sensors130A-E (block 322). Subsequently, the processor 100 may determinewhether the number of cycles of the syringe pump 124 during thepressurization method 300 has exceeded a predetermined threshold value(e.g., 10 cycles) (block 324), and, if so, may terminate pressuretesting with a failure indication (block 326). If, however, theprocessor 100 determines that the cycle limit has not yet been reached,then the processor may proceed back to block 310, as indicated by thearrow 328, and calculate PE once more based on the latest pressuremeasurement.

The use, if any, of ordinal indicators, e.g., (a), (b), (c) . . . or thelike, in this disclosure and claims is to be understood as not conveyingany particular order or sequence, except to the extent that such anorder or sequence is explicitly indicated. For example, if there arethree steps labeled (i), (ii), and (iii), it is to be understood thatthese steps may be performed in any order (or even concurrently, if nototherwise contraindicated) unless indicated otherwise. For example, ifstep (ii) involves the handling of an element that is created in step(i), then step (ii) may be viewed as happening at some point after step(i). Similarly, if step (i) involves the handling of an element that iscreated in step (ii), the reverse is to be understood.

It is also to be understood that the use of “to,” e.g., “a valve toswitch between two flow paths,” may be replaceable with language such as“configured to,” e.g., “a valve configured to switch between two flowpaths”, or the like.

Terms such as “about,” “approximately,” “substantially,” “nominal,” orthe like, when used in reference to quantities or similar quantifiableproperties, are to be understood to be inclusive of values within ±10%of the values specified, unless otherwise indicated.

In addition to the claims listed in this disclosure, the followingadditional implementations are to be understood to be within the scopeof this disclosure:

Implementation 1: A system including: a flow cell to support analytes ofinterest; a selector valve coupled to the flow cell to select a flowpath through the flow cell the flow path being one of a plurality offlow paths selectable by the selector valve; a pump coupled to the flowcell to pressurize a fluid in the selected flow path in accordance witha prescribed test protocol; a pressure sensor coupled to the flow pathto detect pressure in the selected flow path and to generate pressuresignals based on the detected pressure; and processing circuitry toaccess the pressure data and to determine whether the selected flow pathmaintains pressure in a desired manner.

Implementation: 2: The system of implementation 1, in which the pumpincludes a syringe pump.

Implementation: 3: The system of implementation 1, in which the fluidincludes air.

Implementation: 4: The system of implementation 1, in which the pumppressurizes the selected flow path in a plurality of pressure steps.

Implementation: 5: The system of implementation 1, in which the selectorvalve successively selects different flow paths of the plurality of flowpaths through the flow cell to be pressure tested in accordance with theprescribed test protocol.

Implementation: 6: The system of implementation 5, in which theplurality of flow paths includes a first flow path through one channelof the flow cell, and a second flow path through a second channel of theflow cell different from the first flow path.

Implementation: 7: The system of implementation 6, in which theplurality of flow paths includes a third flow path that includes boththe first and the second flow paths.

Implementation: 8: The system of implementation 1, in which the selectorvalve is coupled to a bypass line that bypasses the flow cell, and inwhich the selector valve also selects the bypass line to be pressuretested in accordance with the prescribed test protocol.

Implementation: 9: The system of implementation 1, including a secondvalve coupled to the selector valve to fluidly isolate the selected flowpath for pressure testing.

Implementation: 10: A system including: a flow cell to support analytesof interest; a selector valve coupled to the flow cell to select a flowpath through the flow cell the flow path being one of a plurality offlow paths selectable by the selector valve; a pump coupled to the flowcell to pressurize a fluid in the selected flow path in accordance witha prescribed test protocol; a pressure sensor coupled to the flow pathto detect pressure in the selected flow path and to generate pressuresignals based on the detected pressure; and processing circuitry tocommand the selector valve successively to select different flow pathsof the plurality of flow paths through the flow cell in accordance withthe prescribed test protocol, and to access the pressure data and todetermine whether each of the selected flow paths maintains pressure ina desired manner.

Implementation: 11: The system of implementation 10, in which the fluidincludes air.

Implementation: 12: The system of implementation 10, in which the pumppressurizes each of the selected flow paths in a plurality of pressuresteps.

Implementation: 13: The system of implementation 10, in which theplurality of flow paths includes a first flow path through one channelof the flow cell, and a second flow path through a second channel of theflow cell different from the first flow path.

Implementation: 14: The system of implementation 13, in which theplurality of flow paths includes a third flow path that includes boththe first and the second flow paths.

Implementation: 15: The system of implementation 10, in which theselector valve is coupled to a bypass line that bypasses the flow cell,and in which the selector valve also selects the bypass line to bepressure tested in accordance with the prescribed test protocol.

Implementation: 16: A method including: implementing a stored prescribedtest protocol that includes: (a) selecting a flow path from a pluralityof flow paths through a flow cell in accordance with a prescribed testprotocol; (b) actuating a pump to pressurize a fluid in the selectedflow path; (c) generating pressure data representative of the pressurein the selected flow path; and (d) processing the pressure data todetermine whether the selected flow path maintains pressure in a desiredmanner.

Implementation: 17: The method of implementation 16, in which the pumppressurizes the selected flow path in a plurality of pressure steps.

Implementation: 18: The method of implementation 16, including repeating(a)-(d) for different flow paths through the flow cell to separatelydetermine whether each selected flow path maintains pressure in adesired manner.

Implementation: 19: The method of implementation 18, in which theplurality of flow paths includes a first flow path through one channelof the flow cell, and a second flow path through a second channel of theflow cell different from the first flow path.

Implementation: 20: The method of implementation 18, in which theselector valve is coupled to a bypass line that bypasses the flow cell,and in which the selector valve also selects the bypass line to bepressure tested in accordance with the prescribed test protocol.

It should be appreciated that all combinations of the foregoing concepts(provided such concepts are not mutually inconsistent) are contemplatedas being part of the inventive subject matter disclosed herein. Allcombinations of the claimed subject matter appearing at the end of thisdisclosure are contemplated as being part of the inventive subjectmatter disclosed herein. It should also be appreciated that terminologyexplicitly employed herein that also may appear in any disclosureincorporated by reference should be accorded a meaning most consistentwith the particular concepts disclosed herein.

What is claimed is:
 1. A system comprising: an interface to fluidicallyconnect with a flow cell that to support analytes of interest in ananalysis system, the fluidic interface including a plurality of flowpaths and a plurality of effluent lines, each flow path to fluidicallyconnect with one or more channels of the flow cell when the flow cell ismounted in the analysis system and each effluent line to fluidicallyconnect with one of the channels of the flow cell when the flow cell ismounted in the analysis system; a selector valve fluidically connectedwith plurality of flow paths, the selector valve to controllably selectone of the flow paths; one or more pumps, each pump fluidicallyconnected with one or more of the effluent lines; a pressure sensor influidic communication with the selected flow path, the pressure sensorto detect pressure in the selected flow path and to generate pressuredata based on the detected pressure; and control circuitry, the controlcircuitry having one or more processors and a memory to storecomputer-executable instructions which, when executed by the one or moreprocessors, control the one or more processors to: control the one ormore pumps so as to pressurize the selected flow path according to aprescribed test protocol; cause, as part of the test protocol, the oneor more pumps to pressurize the selected flow path in a stepwise manner,with each pressure step having a higher pressure than the previouspressure step; and access the pressure data and to determine whether theselected flow path maintains pressure in a desired manner.
 2. The systemof claim 1, wherein the one or more pumps comprises at least one syringepump.
 3. The system of claim 1, wherein the fluid comprises air.
 4. Thesystem of claim 1, wherein the memory is to store furthercomputer-executable instructions which, when executed by the one or moreprocessors, further control the one or more processors to cause theselector valve to successively select different flow paths of theplurality of flow paths to be pressure-tested in accordance with theprescribed test protocol.
 5. The system of claim 4, wherein theplurality of flow paths comprises a first flow path through one channelof the flow cell when the flow cell is mounted to the interface, and asecond flow path through a second channel of the flow cell when the flowcell is mounted to the interface, the second flow path different fromthe first flow path.
 6. The system of claim 5, wherein the plurality offlow paths comprises a third flow path that includes both the first andthe second flow paths.
 7. The system of claim 1, wherein the selectorvalve is further fluidically connected with a bypass line that bypassesthe flow cell, and wherein the memory is to store furthercomputer-executable instructions which, when executed by the one or moreprocessors, further control the one or more processors to cause theselector valve to select the bypass line to be pressure-tested inaccordance with the prescribed test protocol.
 8. The system of claim 1,comprising a second valve that is fluidically connected with an inlet tothe selector valve, the second valve to seal the selected flow path atthe second valve for pressure-testing of the selected flow path betweenthe second valve and the pump.
 9. A system comprising: a flow cell tosupport analytes of interest; a selector valve fluidically connectedwith the flow cell, the selector valve to controllably select a flowpath through the flow cell from a plurality of flow paths through theflow cell that are selectable by the selector valve; one or more pumpsfluidically connected with the flow cell, the one or more pumps topressurize a fluid in the selected flow path in accordance with aprescribed test protocol; a pressure sensor fluidically connected withthe selected flow path, the pressure sensor to detect pressure in theselected flow path and to generate pressure data based on the detectedpressure; and control circuitry, the control circuitry having one ormore processors and a memory to store computer-executable instructionswhich, when executed by the one or more processors, control the one ormore processors to: cause the selector valve to successively selectdifferent flow paths of the plurality of flow paths through the flowcell in accordance with the prescribed test protocol, cause the one ormore pumps to be actuated so as to successively pressurize the selectedflow paths in accordance with the prescribed test protocol, cause, aspart of the test protocol, the one or more pumps to pressurize each ofthe selected flow paths in a stepwise manner using a plurality ofpressure steps, each pressure step for each selected flow path having ahigher pressure than the previous pressure step for that selected flowpath, access the pressure data, and determine whether each of theselected flow paths maintains pressure in a desired manner based on thepressure data.
 10. The system of claim 9, wherein the fluid comprisesair.
 11. The system of claim 9, wherein the one or more pumps includesat least one syringe pump.
 12. The system of claim 9, wherein theplurality of flow paths comprises a first flow path through one channelof the flow cell and a second flow path through a second channel of theflow cell, wherein the second flow path is different from the first flowpath.
 13. The system of claim 12, wherein the plurality of flow pathscomprises a third flow path that includes both the first and the secondflow paths.
 14. The system of claim 9, wherein the selector valve isfurther fluidically connected with a bypass line that bypasses the flowcell, the selector valve to controllably select the bypass line to bepressure tested in accordance with the prescribed test protocol.
 15. Amethod comprising: implementing a stored prescribed test protocol thatcomprises: (a) selecting a flow path from a plurality of flow pathsthrough a flow cell in accordance with the prescribed test protocol; (b)actuating a pump to pressurize a fluid in the selected flow path in astepwise manner using a plurality of pressure steps; (c) generatingpressure data representative of the pressure in the selected flow path;and (d) processing the pressure data representative of the pressure inthe selected flow path to determine whether the selected flow pathmaintains pressure in a desired manner.
 16. The method of claim 15,wherein the pump is a syringe pump.
 17. The method of claim 15, furthercomprising repeating (a) (d) for different flow paths through the flowcell to separately determine whether each selected flow path maintainspressure in a desired manner.
 18. The method of claim 17, wherein theplurality of flow paths comprises a first flow path through one channelof the flow cell and a second flow path through a second channel of theflow cell, wherein the second flow path is different from the first flowpath.
 19. The method of claim 17, further comprising selecting a bypassline to be pressure tested in accordance with the prescribed testprotocol, actuating the pump to pressurize a fluid in the bypass line,generating pressure data representative of the pressure in the bypassline, and processing the pressure data representative of the pressure inthe bypass line to determine whether the bypass line maintains pressurein a desired manner, wherein the bypass line does not flow through theflow cell.